The present invention relates to a front suspension structure of an automotive vehicle, and in particular, relates to a double-wishbone type front suspension structure of an automotive vehicle.
As the double-wishbone type front suspension structure of the automotive vehicle, there exists a structure in which respective vehicle-body-side end portions of two arms (an upper arm and a lower arm) which are arranged vertically and extend in a vehicle width direction are pivotally supported at a vehicle-body-side member, respective wheel-side end portions of the two arms are connected to a knuckle member (a wheel support) which rotatably supports a wheel via respective ball joints, and a damper unit is provided between a vehicle body and the lower arm. This structure has been used widely.
Herein, another type of structure as the double-wishbone type front suspension structure, in which the damper unit is arranged such that it is inclined toward a caster axis or a kingpin axis, has been used as well, which is disclosed in Japanese Patent Laid-Open Publication No. 2006-264409, for example.
A damper unit (10) disclosed in the above-descried patent document is configured such that its axial line (B) is inclined, in a plan view, toward a side having a caster axis so that its upper portion is positioned rearward (see FIG. 2 of the above-described patent document). Further, a lower arm (6), to which a lower end portion of the damper unit (10) is connected, is arranged such that it slants forward for preventing deterioration of an anti-dive geometry or the like (see FIG. 5). That is, the damper unit (10) of the above-described patent document is arranged in a rearward-and-downward slant state relative to the lower arm (6) in a side view.
In the above-described structure, however, there easily occurs twisting at a mount rubber which is provided at a connection portion of the an upper end (10a) of the damper unit (10) to the vehicle body when a vertical-direction load acts on the lower arm (6) from the wheel by way of a wheel support (8), for example, so that there is a concern that it may become difficult for the damper unit (10) to smoothly move vertically because of generation of a load which changes nonlinearly relative to the vertical move of the damper unit (10) or the like.
Meanwhile, there exists a front suspension structure in which the damper unit is not inclined toward the caster axis as shown in Japanese Patent Laid-Open Publication No. H05-262111. According to a suspension device disclosed in this patent document, a spring/shock absorber unit (30) as the damper unit is provided in a longitudinal direction such that it is inserted into an air duct (13) for brake-device cooling and also connected to a lower arm (21) via a link mechanism (50), so that a load applied from a wheel side can be transmitted to the spring/shock absorber unit (30) by way of the lower arm (21) and the link mechanism (50) which slants forward in a side view, and the layout property of the suspension device can be improved.
However, since the above-described link mechanism (50) is provided to slant between the lower arm (21) and the spring/shock absorber unit (30), there is a problem that the number of components or movable portions may improperly increase.
That is, there is room for improvement in compatibly attaining improvement of the wheel-support rigidity for improving the vehicle handling stability and the wheel's smooth vertical move for improving the road-following property and the riding conformability in the structures disclosed in the above-described patent documents.